Electrical squib separation device



Filed Sept. 27, 1960 R a R U m m A 2 W m I. S G J. |l Y II. F N Q m G 7 l N l. 8 A F a 5 l B 5 7 9 5 6 6 l a 5 5 5 r II \\|\.\\\\4 1/ l I 2 3 5 I 3 C 2 l 4 4 7 2 m m.. 7 4 0 4 9 l I. 3 (3 a 1 3 l l 9 a A 3 5 m 4. 3 M 5 :1 1/ 5 2 l \H 2 m 7 s s I 8 H 2 W 5 7 5 W 3 8 3,080,815 ELECTRICAL SQUIB SEPARATION DEVKIE Anthony J. Sinishauser, China Lake, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Sept. 27, 1960, Ser. No. 58,862 4 Claims. (Cl. 102-49) (Granted under Title 35, U.S. Code (E52), sec. 266) The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a device for separating two objects and in particular to a device which separates two objects without imparting perturbation to the separated objects or rupturing the separation device.

Separation devices having a cavity formed by two slidably disposed cylinders, each closed at one end and connected to an object to be separated, are known in the art. It has been the practice in the use of such devices to dispose an ignition squib in the cavity and fill the space between the squib and cavity walls with a gas producing material such as double-base propellant or black powder.

Two primary difficulties have been encountered with devices of this type. The first is rupture of the cavity walls and the second is the inducement of large shock forces or perturbations to the separated objects. Both of these difficulties arise because of the large uncontrolled quantity of gas that is released primarily by the gas producing materi l and supplemented in part by the ignition squib.

Rupture is largely the result of completely filling the cavity of the separation device with gas producing material which confines the initially expanding gases to a very small volume and results in high initial pressures. These high initial pressures impart large forces to the cavity walls resulting in rupture thereof. Previous methods of overcoming rupture have been by increasing the thickness of the cavity walls; however, this increases the overall Weight which is generally undesirable.

The large shock forces or perturbations imparted to the separated objects are primarily due to the large difference between the cavity pressure and the ambient pressure at the instant the two slidably disposed cylinders become separated. At the instant of separation, the gas in the cavity, which is at a relatively high pressure, suddenly expands and sets up shock waves which agitate the separated objects resulting in undesirable uneven separation.

The present invention obviates the disadvantages of the prior art by providing an initial expansion volume in the cavity of the separation device and by venting the cavity gas prior to separation of the slidably disposed cylinders. This initial expansion volume is provided by employing a squib designed to occupy less than the entire cavity volume and the venting is obtained by provicling slots in the periphery of the inner cylinder adjacent the openend thereof. By providing an initial expansion volume, lower initial pressures are realized which do not cause rupture and by providing venting slots, a low diflFerential pressure is obtained upon separation of the cylinders which does not impart shock forces or perturbations to the separated objects.

An object of the present invention is to provide an inexpensive and reliable separation device.

Another object is to provide a separation device that will not rupture upon actuation.

Still another object is to provide a separation device that does not impart perturbations to the objects which are separated.

5 sure thereby preventing rupture of the separation device and shock to the separated objects.

Other objects and many of the attendant advantages of this invention will become readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an enlarged side elevation sectional view of the separation device of the present invention; and

FIG. 2 is a sectional view taken on line 22 of FIG. 1.

In FIGS. 1 and 2 are shown the separation device of the present invention. The primary elements of this device consist of outer member 11, inner member 13 and squib 15. Inner member 13 is slidably disposed within outer member 11 thereby forming an enclosed cavity. Squib 15 is mounted in the enclosed cavity and upon ignition thereof the released gases cause separation of the inner and outer members and the corresponding objects to which they are connected.

Outer member 11 consists of plate member 19 and cylinder 21 which may be integral (as shown) or separate structures which are rigidly connected as by weld, bolts or other suitable fastening means, The general plane of plate member 19 is substantially normal to the axis of cylinder 21 and together form a cavity closed at one end. Plate member 19 is circular and consists of inner plane surface 23, outer surface 25, general radially extendmg surface 25 is shaped to correspond with the contour of the object to which it is, connected which is illustrated 5 by broken lines 35. Flange 29 provides base material by which outer member 11 is connected to the object 35 as by means of weld 37. Cylinder 21 has an inner cylindrical surface 39 and exterior threads 41. Cylindrical;

collar 43 has internal threads 45, which mate with threads rate structures which are rigidly connected at by weld,

The general plane of plate member 53 is substantially normal to the- 0 bolts or other suitable fastening means.

axis of cylinder 55 and together form a cavity closed at one end. Plate member 53 is circular and consists of inner plane surface 57, outer surface 59 and generally 5 radially extending peripheral flange 61. Outer surface 59 isshaped to correspond with the contour of the object to which it is connected as illustrated by broken lines 63. Flange 61 provides material by which inner member 13 is connected to the object as by means of weld 65.

0 The outside diameter of cylinder 55 is slightly less than the inside diameter of cylinder 21 such that they are slidable with relation to each other and still prevent excessive gas leakage. The length of cylinder 55 is adjusted so that when fully inserted in cylinder 21, there is space be- 5 tween the end of cylinder 21 and flange 61. In the wall of cylinder 55' longitudinally extending slots 79 and 80 are provided which extend from the end to approximately midway of the length of the cylinder. Preferably these slots are oppositely disposed; however, they may be ar- 0 ranged in any other manner provided the net reactive forces are negligible so that virtually no lateral motion peripheral flange 29 and shoulders 31 and 33. Outer 41; and a radially extending flange 47. A device 49,- which may be a mercury nutation damper having an me ls will be imparted to the separation deviceand the objects ment '73, gas producing material 75 and insulated lead wires 77 and 78; Casing 71 is entirely closed, is made of hardened copper or other material having similar heat,

strength and ductility characteristics and u-ponignition at least one hole is punctured therein, without fragmentation thereof, to allow escape of the generated gases. Gas

producing material 75 is disposed in the casing and may.

be lead azide or'other combustible material that has a low'ignition temperature and a rapid rate ofburning. Ignition element 73 is imbedded in material 75 and is resistive to current flow so that upon the application of a potential difference across insulated lead wires 77 and 78, the'tem'perature of the element exceeds the ignition temperature of-the material. Element 73 is preferably coated with the material t'o'assure' ignition by intimate atmosphere.

'4 against surfaces 23 and 57 with corresponding forces causing separation of members 11 and 13. 'As members 11 and 13 progressively separate, slots 79 and 80 become exposed to atmosphere and vent the gas in the cavity to At the instant of venting, the'momcntum of separating members 11 and 13 and the objects, denoted by. lines 35 and 6 3, to which they are respectively connected, is of sufiicient value that they will become completely separated 'andretain residual velocities in opposite directions. Since the. venting takes place While cylinders 21 and 55 are still in slidable contact, there can be no relacontact. Openings are provided in member 11for receiving the lead wires 77 and 78 and are of such size that there is no gas leakage pastthe lead wires when assembled. Lead wire 77 passes through slot 79 and directly to squib 15 through the near side of cylinder 71. Lead wire 78 passes through slot 80 and halfway around squib 15 sofas to enter the same side of casing 71 as lead wire 77 The length of. casing 71 is less than the inside diameter of cylinder 55 and the diameter of casing 71 is less 'tli-anthe longitudinal distance between plane surfaces 23a'n'd 57 whenmember 13 is fully inserted. The lead wires of squib 15 are adjusted and are sufficiently rigid toretain the'ends of the squib approximately equispaced from the interior surface 'ofcylinder 53 and the cylindrical surface of the casing in spaced relation from plane surface 23. 'It istoybe understood that squib 15 may be disposed in the cavity formed by-members 11 and 13 any position so long as gases issuing therefrom may. readily come into contact with the interior surfaces thereof and that other shapes, sizes and designs of squibs may be employed. In addition, ribs or extensions may be attached to the exterior surface of the squib or interior surfaces of members 11 and13 to maintain the desired separation; j I

' From this it can be seen that a clearancevolume 81 is provided between "the exterior surface of squib15. and the interior surfaces of the cavity formed by members 111 and 13 for purposes hereinafter described. The operation of the device shown in FIGS. 1 and 2 is as followsr Upon the application of a voltage across lead wires 77 and 78, element 73 is heated and ignites material 75 which completely burns almost instantaneously. "Since squib 15 is 'supported'by the ,lead wires so that there is considerableclearance about its entire outer -surface, the gas generated by material 75 rapidly expands.

into clearance volume 81. It should be particularly noted that the entire cavity volume defined by members 11, and

I3 is not occupied and the generated gas is fr'ee'to expand to a pressure much lower than would be the' case if the gas producing material were strictly confined.

The relationship between the clearance volume and the volume ofthe squib (which is generally directly related to the energy released by the gas producing material) is such thatin the expansion process the gas pressure'rises to a value which. is considerably lessthan that which tive lateral motion of these cylinders which may be caused by the venting. In addition, since the venting slots are oppositely disposed, the resulting lateral force is approximately zero and there will be negligible lateral motion of membersll and 13 and the corresponding ob jeots to which theyare connected. At the'instant of complete separation of members 11 and 13, the cavity is at approximately atmospheric pressure and there is virtually no gas expansion and no shock waves which could' agitate the separated members and objects attached thereto.

The above-described separation device is particularly of the type described in patent application Serial No. 77,478, filed December. 21, 19.60, by Firth Pierce for Scanning Method for'Firing Rocket Stage? When it is used to separate solid propellant rocketmotor stages, one

of which is. retromounted, bolts 85 and 87v may be; at-;

tached respectively, to outer surfaces 25 and 59. Cylindrical openings, which are larger than the outside thread; diameters, are provided inthecasings of the rocket motors and the bolts. are inserted therethrough. Plates. 19 and 53 are;welded about, their entire periphery to prevent gas leakage when the rocket motors are ignited. After assembly, the, igniter elements of therocket motors, which have femalethreads corresponding with the threads of bolts 8,5'and 87, are mounted thereon and in abutment with the inner; surface 'of'the rocket motor casings.

Obviously many modifications and variations of the present invention are possible in the light of the above. teachings. Itis therefore to be understood that within the -scope of the-appended claims the invention may be practiced otherwise than as specifically described.

' What is claimed is:

1. A device for, separating a pair of rocket stages without imparting perturbations thereto, said device comprising afirst hollow cylinder closed at one end, a second hollow cylinder closed atone end, said second cylinderv having. a major portion thereof disposed within said first cylinder and closely'fitted thereto with a slidable fit, said cylinders forming an enclosed cavitytherebetween, said slidable fitconstituting the sole connection between said cylinders,

a cylindrical squib closed at both ends and having an outside diameter less than the distance between the interior surfaces of. the closed ends of said cylindersand a length less than the in sider diameter of said second cylinder and having electrical lead lines, said lead lines being mounted insaid firstcylinder and solely supporting said squib such that the closed ends thereof are approximately equispaced from the. interior cylindrical surface of said second cylinder and the cylindrical surface of said squib is spaced from said interior. surfaces thereby forming an expansi en volume between the, exterior surface of said squib would. rupture the wallof cylinder 21. In addition, since 7 position with relation to memberll by lead .wires77 and.

7.8 and will notbe, free to strike or. agitate the separation The instantaneously generated gas creates a pressure and the interior surfaces of said enclosed cavity, said second cyl nder having venting means in. the. cylindrical wall adjacentthe open end thereof.

2. The device, of claim 1 wherein said: venting means comprises a plurality of longitudinally extending slots inthe wall of said second cylinder which extend from the end thereof to approximatelymidway of the length of the second cylinder, and said electrical lead lines pass through said slots.

3. A mechanism for completely separating vtwo rocket stages without imparting perturbations thereto, said mechanism, comprising a first cup-like member having an open end and a bottom secured to one of the stages, a

second cup-like member having an open end and a bottom secured to the other of said stages, said second cup-like member having a major portion thereof disposed within said first cup-like member with a close-fitting slidable fit between said members, said slidable fit constituting the sole connection between said members, said members together forming a closed chamber therebetween, said second cup-like member having a pair of diametrically disposed slots therein extending from the open end thereof to approximately midway the length thereof, a pair of wires extending into said chamber, one of said wires passing through one of said pair of slots and the other wire passing through the other slot, and a gas producing device supported within said chamber in spaced relation to the walls thereof, said wire being connected to said device and comprising the sole support therefor.

4. A mechanism slidably interconnecting a pair of rocket stages and adapted for gradual complete separation thereof without imparting perturbations to the stages, said mechanism comprising a first cup-like member secured to one of said stages and having an inner cylindrical wall, a second cup-like member secured to the other of said stages and having a cylindrical wall with an outside diameter substantially equal to the diameter of the inner cylindrical wall of said first cup-like member, said second member having a major portion of its cylindrical wall disposed within said first member with a close-fitting slidable fit between the walls of said members, said walls constituting the sole connection between said stages, said members defining a chamber therebetween, said cylindrical wall of said second member having a pair of diametrically opposite slots therethrough, a pair of electrical lead wires extending into said chamber, one of said wires passing through one of said slots and the other wire passing through the other of said slots, an electrically-ignitable smoke-producing squib of lesser dimensions than said chamber, said squib being connected to said wires and supported solely thereby within said chamber in spaced relation to the walls thereof; whereby gas released from the gas-producing squib expands into said chamber and causes gradual sliding separation of said members, and said slots vent the gas to atmosphere prior to the complete separation of the members.

References Cited in the file of this patent UNITED STATES PATENTS 314,036 Marvin Mar. 17, 1885 2,206,777 Kee July 2, 1940 2,726,576 Musser Dec. 13, 1955 2,756,634 Allen et a1. July 31, 1956 2,815,698 Burrows Dec. 10, 1957 2,883,910 Nessler Apr. 28, 1959 

1. A DEVICE FOR SEPARATING A PAIR OF ROCKET STAGES WITHOUT IMPARTING PERTURBATIONS THERETO, SAID DEVICE COMPRISING A FIRST HOLLOW CYLINDER CLOSED AT ONE END, A SECOND HOLLOW CYLINDER CLOSED AT ONE END, SAID SECOND CYLINDER HAVING A MAJOR PORTION THEREOF DISPOSED WITHIN SAID FIRST CYLINDER AND CLOSELY FITTED THERETO WITH A SLIDABLE FIT, SAID CYLINDERS FORMING AN ENCLOSED CAVITY THEREBETWEEN, SAID SLIDABLE FIT CONSTITUTING THE SOLE CONNECTION BETWEEN SAID CYLINDERS, A CYLINDRICAL SQUIB CLOSED AT BOTH ENDS AND HAVING AN OUTSIDE DIAMETER LESS THAN THE DISTANCE BETWEEN THE INTERIOR SURFACES OF THE CLOSED ENDS OF SAID CYLINDERS AND A LENGTH LESS THAN THE INSIDE DIAMETER OF SAID SECOND CYLINDER AND HAVING ELECTRICAL LEAD LINES, SAID LEAD LINES BEING MOUNTED 